Presentation on theme: "Anurans in the semi-arid Caatingas: convergence, divergence, and implications for global warming Carlos A. Navas Universidade de São Paulo - Brazil."— Presentation transcript:
Anurans in the semi-arid Caatingas: convergence, divergence, and implications for global warming Carlos A. Navas Universidade de São Paulo - Brazil
* According to models by J. Marengo et al., CCST/INPE - Brazil Projections of Climate Change in North Eastern Brazil for * - Rainfall reduction, more intense by Increase in air temperature by 2-3 C in , and by more than 4 C by Increase in the frequency of hot days and nights, and heat waves. - Water deficits varying between 2-3 mm/day in and 6-9 mm/day by Aridization and possible desertification in parts of the semiarid land I - Why caatingas, why anurans Brazilian Institute for Geography and Statistics
Two-month period Year Interval for prediction More rain Less rain Models by J. Marengo et al., CCST/INPE - Brazil
Rhinella granulosa Corythomantis greeningi Phyllomedusa nordestina Dendropsophus minutus Scinax eurydice Leptodactylus ocellatus Proceratophrys cristiceps Physalaemus gracilis Pseudis bolbodactyla Adenomera sp. Dermatonotus muelleri Rhinella jimi Despite its semi-arid nature, the Caatinga is home to 40+ anuran species
After aridizationBefore aridization After further aridization? Likely, anurans have colonized the Caatinga via permanence during a process of aridization lasting years
So, why Caatingas, why anurans… Caatingas are a recent semi-arid biome, present only in Brazil and in great risk due to climate change. Anurans are expected to be at particular risk in the predicted scenarios. The anuran community of the Caatingas reflects a diverse and evolutionarily-recent subset of lineages derived from Cerrado, Atlantic Forest and Amazonian Rainforest. We do not know if these species and populations differ from related stock from more moderate biomes.
Why Caatinga anurans are vulnerable to climate warming and eventually… Why semi-arid anurans are vulnerable to climate warming What is next? How to start?
Do Caatinga anuran species share enough aspects of natural history as to propose valid generalizations about how they will be affected by climate change? Valid generalizations: common consequences of climate change due to shared aspects of natural history and physiology. Can we propose valid generalizations for anurans is the Caatinga?
Conservation of habits and physiology? Leptodactylus ocellatus
RH= 40% Humid cotton fluff Navas, Jared et al Some species displays integrated physiology and behavior that result in keen ability to detect humid microhabitats Specialization on microhabitat selection and sensorial physiology? Corytomantis greeningi 1 cm.
Prates & Navas, 2009 Habitat generalist specialized on water uptake? Bufo jimmi
Behavioral conservation and physiological specialization? Juvenile R. jimmi and R. granulosa B. calamita, M. Emmers B. marinus, R. Shine B. americanus, Lookoutnow B. alvarius, J.P. Clare B. Boreas (Wildherps) B. granulosus, C. Jared > 45 °C
Navas, Carvalho et al., 2007 CS residual activity (% of normal at 30 o C) Incubation time at 50 o C (min) R. granulosa R. jimi R. icterica R. granulosa (juvenile) Behavioral conservation and physiological specialization? Juvenile Bufo jimmi and B. granulosus
Is water proofing enough? Phyllomedusa ? P. bicolor Amazonian forest P. distincta Atlantic forest P. burmeisteri Semi-deciduous forest hypochondrialis group burmeisteri group P. ayeaye Cerrado (restricted) P. nordestina Caatingas P. azurea Chaco, Cerrado
Aestivation seems diverse among Caatinga anurans Proceratophrys, Dermatonotus and others, Typical aestivation? Pleurodema, Atypical aestivation? Bufo jimmi, no aestivation? Bufo granulosus, facultative aestivation?
Time after last rain (months) Depth (cm) Pereira et al., não publicado ActiveAestivating Speed (m/s) RainsDrought Soluble Protein concentration (mg/g of humid tissue) Possible specialization: Aestivation with vertical migration in Pleurodema 90% RH
Anuran life in the Caatinga involves behavioral, ecological and physiological traits that vary in relative importance among lineages. Due to microhabitat choice and behavior, species are likely to differ in the type and magnitude of physiological challenges. Conclusions
Proposal Rainfall reductionMicrohabitat specialists Increase in air temperature by 2-4 CSpp. with diurnal juveniles Water deficits (longer dry seasons) Typical aestivators Aridization and possible desertificationRefugia specialists Predicted climatic changeExpected highest impact Given this diversity, it is difficult to generalize about consequences of climate change for Caatinga anurans. The most productive generalizations regarding impact of climate change on semi-arid anurans may be based on ecological convergence across lineages.
Cited collaborators Carlos Jared (Butantan) Marta Antoniazzi (Butantan) Fernando R. Gomes (UNESP) Jose E. Carvalho (UNESP) Hanna Suzuki (Butantan) Titon Braz Jr.(UNESP) Monique Simon(USP) Isabel C. Pereira(USP) Ivan Prates(I. Butantan) Field assistance Francisco de Assis Rodriguez Research Program on Global Climate Change